This project builds, describes, and examines complex computer models of the part of cardiac metabolism which makes ATP (glycolysis, the Krebs cycle, etc.), its physiological control, and how it is deranged by ischemic heart disease. This project year we expect to add to these models detailed mechanisms of glycogen metabolism, fatty acid oxidation, and perhaps some other related metabolic processes. We expect to complete and write up models of experimental preparations in which sudden jumps in perfusate pH or workload were studied, and to start simulating one which also was perfused with fatty acids. We hope to further improve our model-building software (with attention to compartational efficiency) and techniques (with emphasis on formalizing a presently intuitive procedure in terms of standard computer techniques such as nonlinear programming or artificial intelligence).